These compounds each functioned as irreversible inactivators of the ASADH isolated from Candida albicans (C. albicans), a pathogenic fungal species. Changes in the identity of R₂ result in higher affinity, increased inactivation rates, and improvements in the ratio of inactivation rate (k_inact) to affinity (K_i) that serves as a measure of covalent inactivator efficiency (Table 1, top). Further increases in target affinity are observed with changes to R₁ (Table 1, bottom). ASADH: aspartate β-semialdehyde dehydrogenase.